Final answer:
The correct sequence of rock deformation as stress is increased is elastic, then ductile, and finally brittle. Rocks initially behave elastically, but with increased stress, they become ductile, bending and folding without fracturing. If stress continues to increase, rocks will eventually behave in a brittle fashion and fracture.
Step-by-step explanation:
The correct sequence of deformation styles that a rock will exhibit as the amount of stress applied to the rock is increased is: elastic→ductile→brittle. When rocks are subjected to stress, they initially respond in an elastic manner, meaning they can return to their original shape after the stress is removed. This behavior continues until the rock reaches its elastic limit, at which point, if the stress continues to increase, the rock will start to deform plastically. This plastic or ductile deformation implies that rocks bend and fold without fracturing, and they do not regain their original shape once the stress is released. If the stress increases even further, rocks will eventually fracture in a brittle manner.
Ductile deformation typically occurs at greater depths within the Earth where temperatures and pressures are higher, allowing for more plastic behavior. Conversely, brittle deformation is more prevalent near the surface where lower pressures and temperatures make rocks more likely to fracture.
The sequence of rock deformation from elastic to ductile to brittle is important for understanding the geologic processes that shape the Earth. It also helps geologists determine the conditions under which rocks were deformed by analyzing structures such as folds and faults, which are indicative of the type of stress the rock has experienced.